After designing three versions, [dgcx] eventually ended up with a one-FPGA implementation of a PDP-10 and an awesome PDF writeup. Although PDP-10 emulators do exist, this project isn’t an emulation – the system actually has the 36-bit word length of the original, implemented on five 4096 kilobit SRAM chips. This is a fully functioning replica, and even has CHAOSNET implemented with a small Ethernet controller.

With very old computers, it’s very hard to find software to run on these machines. This was the same problem the builder of the tiny Cray had. If any Hack A Day readers know where [dgcx] could find some old DEC software, be sure to post something in the comments. Otherwise, he may just get started porting the first edition of Unix.

Well, for me, it’s the thought that we are doing things that were unimaginable in my childhood. We are taking a computer and putting it inside a computer. Not only that, I could run THOUSANDS instances of these computers if I were so inclined.

Getting 1st Edition Unix wouldn’t help you get any software… you’d be much better off with TOPS-20 or TOPS-10 or ITS, all of which are available on the Internet, AND were designed for 36-bit PDP-10s, not the 16-bit PDP-11s.

DGCX, if you happen to read this, it would be awesome if you could post the original Eagle (or equivalent) files for the FPGA PCB on your site; suitable for sending to a PCB manufacturer. I’m sure a few people will appreciate it. Publicly available PCB designs for FPGAs are almost non-existent.

People who’ve never met the PDP10 shouldn’t assume that it is “similar” to a PDP11 just because the numbers are close together. The PDP10 was DEC’s “mainframe” computer, with an architecture featuring 36-bit words and word addressability. Getting C to run on the PDP10 was a major challenge, and I don’t think they ever ran any flavor of unix. DEC released both of their major operating systems (TOPS10 and TOPS20) for hobbyist use quite a long time ago, and there have been software-based emulators as well (running on “x86 micromachines”, many times faster than the fastest DEC HW ever made.)
The original PDP6 (DEC’s first 36bit computer, more or less) was supposed to have been about 3000 gates; I’ve always wondered if it was an architecture suitable for cramming into a single chip FPGA. (Things are complicated by the importance of the memory pager, which was less transparently documented…)

Everyone seems to have missed the fact that I *do* have software for the machine. It runs a custom version of ITS. It runs it well enough that I routinely sit upstairs, connected to the machine via TELNET running over CHAOSNET, editing in EMACS.

Unfortunately this is NOT a fully functional PDP-10… it is lacking that awesome front panel display of blinkn lights!
We used to watch those from afar to monitor the 3d rendering programs. It was easy to pick up the patterns. Westworld, Tron Light Sail, Flight of The Navigator, Explorers and others were made using one (with the Foonly doing much of the heavy lifting).

When looking for software for this, you might consider checking with anyone who rescues old big iron. One such group is RCS/RI. I know they have an actual PDP-10, so I would imagine they’ve got some software for it too.

A PDP-10 was a 100-user mainframe (with internet connectivity, sort of) in the same timeframe that the biggest PDP-11s supported maybe 20 users (and didn’t run unix unless you were AT&T or a university.) It was the Vaxen that took over (4.2bsd!!!); PDP11s were never a major force on the Internet (though they got used as appliances like routers and dialin systems and such.)

I dunno. You can look back at the sort of hardware mods that universities made to their mainframe computers (say, like the SAIL “Datadisk” terminals) for more-or-less general use, and it makes a lot of today’s efforts look pretty simplistic. OTOH, those hacks were NEEDED because the alternatives were pretty sucky.

Not quite true. At the height of the PDP-11’s popularity there were an equal amount of them working at the universities, including UCB, they are of course the creators of BSD. It was developed from UNIX.

Internet connectivity was possible both at the dialout/dialin level, and via Ethernet to more capable hardware. They were also used to run textile hardware which is why DEC made that bad decision to sell the line to Mentec.